Since the invention of the integrated circuit (IC), the semiconductor industry has experienced rapid growth due to continuous improvements in the integration density of a variety of electronic components. For the most part, this improvement in integration density has come from repeated reductions in minimum feature size, which allows more components to be integrated into a given area. As the demand for even smaller electronic devices has grown, there has grown a need for smaller and more creative packaging techniques of semiconductor dies.
Conventional package technologies divide a wafer into separate dies and package each individual die; therefore, these techniques are time consuming. The trend of package technique is toward ball grid array (BGA), flip chip (FC-BGA), chip scale package (CSP), and wafer level package (WLP). Wafer level packaging technology can produce dies with extremely small dimensions and good electrical properties, and is currently widely used for its low cost and relatively simple processes.
During the manufacture and operation of the integrated circuit, the die is subjected to mechanical stress, cracks, and moisture penetrations. The stress may be especially high near the edges and the corners of the die. As the die is stressed, active devices, passive devices, and interconnects that make up the integrated circuit are also stressed, which may cause a mechanical failure of the devices or interconnects. In order to prevent such stresses and failures, a guard ring is usually manufactured around the edge of individual circuits. The guard ring on the circuit prevents stresses of the dielectric and metal layers of the circuit. However, guard ring on the circuit level may not be enough to prevent all the possible stresses and damages to the circuits in a package, particularly with WLP technology.
Corresponding numerals and symbols in the different figures generally refer to corresponding parts unless otherwise indicated. The figures are drawn to clearly illustrate the relevant aspects of the various embodiments and are not necessarily drawn to scale.